One year later: A timeline of the Pulse nightclub shooting and its aftermath

A minute-by-minute breakdown of the Pulse nightclub shooting on June 12, 2016.

Mark Bergin, WTSP6:29 AM. EDT June 12, 2017

Brian McDonald, visiting from Frankfort, Ky., writes a personal message on a section of the memorial outside the Pulse nightclub on June 9, 2017. Monday, June 12, 2017, marks one year after the massacre in Orlando, Fla. (Photo: Gregg Newton, AFP/Getty Images)

2:02 a.m.: A gunman walked into the Pulse nightclub with a military-style rifle. He headed for the dance floor while firing shots at random. An off-duty detective working security at the club called for help and tried to stop the gunman.

2:03 a.m.: Back-up began to arrive at Pulse. There was also another shootout.

2:08 a.m.: A team of law enforcement officers went inside of Pulse to start rescuing victims.

2:10 a.m.: A lieutenant cornered the gunman in one of the bathrooms inside Pulse.

2:21 a.m.: A hostage inside of the bathrooms called 911 said the gunman is reloading the rifle.

2:48 a.m.: An officer spoke with the gunman, who said he was wearing a bomb vest. For the next couple of hours, law enforcement worked to tear out windows and concrete walls to pull more people from the building.

5:15 a.m.: The gunman shot at SWAT members, who fire back and kill the gunman.

5:27 a.m.: The remaining survivors inside of the Pulse nightclub are rescued.

We can confirm this is a mass casualty situation. Support from local/state/federal agencies. We expect to brief media shortly.

The FBI checked Omar Mateen’s social media posts, and the role his wife Noor Salman played in the shooting. Law enforcement sources said there's surveillance video of Omar Mateen and his wife buying ammunition.

Emergency call logs released show that victims of the Pulse shooting in Orlando pleaded with sheriff's deputies and dispatchers to save them as they described losing their breath and feeling their bodies go numb from their wounds.